search companion may have been accidentally installed in the computer, or downloaded from the internet without your knowledge. Anytime you download free stuff from the internet you risk installing junk programs like search companion...
click start, control panel, add remove programs, and look at the list.
try to remove, delete search companion, sweepers, cleaners, registry tools, toolbars, free anti virus, and what ever junk is on the drive.
In some cases junk won't delete.
Back up all the personal files to a thumb drive, and consider reloading the operating system. This is sometimes the only sure way to get rid of all the junk on a hard drive.